Exp Clin Endocrinol Diabetes 2013; 121(04): 234-238
DOI: 10.1055/s-0033-1333688
© Georg Thieme Verlag KG Stuttgart · New York

Metabolic Effects of L-carnitine on Type 2 Diabetes Mellitus: Systematic Review and Meta-analysis

A. Vidal-Casariego
1  Sección de Endocrinología y Nutrición, Complejo Asistencial Universitario de León, León, Spain
R. Burgos-Peláez
2  Unidad de Soporte Nutricional, Hospital Vall d’Hebrón, Barcelona, Spain
C. Martínez-Faedo
3  Unidad de Nutrición, Hospital Central de Asturias, Oviedo, Spain
F. Calvo-Gracia
4  Servicio de Endocrinología y Nutrición, Hospital Clínico Lozano Blesa, Zaragoza, Spain
M. Á. Valero-Zanuy
5  Unidad de Nutrición, Hospital 12 de Octubre, Madrid, Spain
L. M. Luengo-Pérez
6  Unidad de Nutrición, Hospital Infanta Cristina, Badajoz, Spain
C. Cuerda-Compés
7  Unidad de Nutrición Clínica y Dietética, Hospital General Universitario ­Gregorio Marañón, Madrid, Spain
› Author Affiliations
Further Information

Publication History

received 26 November 2012
first decision 20 December 2012

accepted 10 January 2013

Publication Date:
21 February 2013 (online)



Carnitine is an endogenous metabolite and exogenous nutrient with a pivotal role in lipid metabolism. Plasma levels of carnitine are reduced in type 2 Diabetes Mellitus (T2DM). The aim was to evaluate the metabolic effects of the administration of L-carnitine in T2DM.


A systematic review was performed. Relevant randomized, controlled-trials trials were searched in Pubmed, Trip Database and Cochrane Library, and selected when they had enough methodological quality assessed with the Jadad scale. Article search strategy included “Carnitine” OR “L-carnitine” AND “Diabetes ­Mellitus” OR “Diabetes mellitus, type 2” OR “Noninsulindependent-diabetes mellitus”. Meta-analysis was performed, and the difference of means calculated with a 95% confidence interval. Heterogeneity was evaluated with the Q statistic.


The systematic review included 4 trials with 284 patients. Oral L-carnitine lowered fasting plasma glucose [−14.3 mg/dl (CI95%  − 23.2 to −5.4); p=0,002], total cholesterol [−7.8 mg/dL (95%CI −15.5 to −0.1); p=0.09], low density lipoprotein [−8.8 mg/dl (CI95% −12.2 to −8.5), p<0.0001], apolipoprotein-B100 [−7.6 mg/dl (CI95% −13.6 to −1.6); p=0.013] and apolipoprotein-A1 [−6.0 mg/dl (CI95% −10.5 a −1.5); p=0.523]. There was no significant heterogeneity. The changes in triglycerides, lipoprotein (a) or HbA1c were not significant.


The administration of L-carnitine in type 2 diabetes mellitus is associated with an improvement in glycaemia and plasma lipids.